This invention relates generally to rotary disc filter machines and, more particularly, to scraper blade apparatus, scraper blade mounting apparatus and filter disc guide and support apparatus for such rotary disc filter machines.
The general construction and arrangement of such rotary disc filter machines is shown and described in many prior patents such as Logue, et al., U.S. Pat. No. 2,932,402 and Oliver, Jr., et al., U.S. Pat. No. 2,964,194. In general, rotary disc filter machines of the type to which this invention relates comprise a semi-cylindrical slurry tank means for receiving and holding a slurry of solid materials suspended in a liquid material. A horizontal rotatable center shaft means extends across the tank means. A plurality of axially spaced annular filter disc units are mounted on the center shaft means for rotation therewith through the slurry in the tank means during a portion of each revolution. Each of the filter disc units comprise an assembly of separate filter disc segments having axially spaced radially and circumferentially extending cake holding side surfaces formed by a porous filter media mounted thereon. Each filter disc segment comprises a radially innermost shaft connecting means having opposed parallel axially spaced flat circumferentially extending side surfaces located in radially inwardly circumjacent juxtaposition to the radially inwardmost end portions of the filter media side surfaces and a radially outermost filter media clamping means having opposed parallel axially spaced flat circumferentially extending side surfaces located in radially outwardly circumjacent juxtaposition to the radially outermost end portions of the filter media side surfaces. The circumferentially adjoining opposed parallel side surfaces of the shaft connecting means and the circumferentially adjoining opposed parallel side surfaces of the filter media clamping means form substantially circumferentially continuous radially innermost and radially outermost axially spaced parallel annular side support surfaces. Vacuum applying means are effective through passages in the center shaft means, the shaft connecting means, and each filter segment to apply vacuum to the filter media side surfaces during rotation through the slurry in the tank means to cause flow of the liquid filtrate material therethrough and to cause the solid cake materials to be held on the filter media side surfaces. Then, during downward rotation of the filter segments toward the slurry tank means, the cake material is removed from the filter media side surfaces by scraper blade means fixedly mounted relative to and extending radially across the filter media side surfaces. The cake removal side of the tank means is provided with alternating axially spaced filter disc unit receiving chambers (slots) connected to the slurry tank means and cake removal slots therebetween defined by a plurality of axially spaced radially extending side plate means and circumferentially extending radially innermost and radially outermost end plate means. The scraper blade means are constructed and arranged to remove the cake from the filter media side surfaces above the cake removal slots and direct the removed filter cake into the cake removal slots as each filter disc segment rotates past the scraper blade means into the disc unit receiving chambers (slots).
Various types of scraper blade apparatus and scraper blade mounting apparatus have been previously employed including, for example, apparatus of the type disclosed in Peterson, et al., U.S. Pat. No. 2,855,083 and Peterson U.S. Pat. No. 3,080,597. The scraper blade apparatus of Peterson U.S. Pat. No. 2,885,083 comprises a curved blade member having curved guide shoes on the radially innermost and outermost end portions of the blade member for supportive sliding engagement with the radially innermost and outermost peripheral circumferentially extending surfaces of the filter disc segments of each filter disc unit. The radially innermost end portion of the blade member is also attached to tank means by a pivotally connected mounting bracket means to enable axial movement of the blade member with the filter disc unit caused by wobble of the filter disc unit during rotation.
The present invention involves improvements in a scraper blade assembly and scraper blade mounting bracket means of the general type of Peterson U.S. Pat. No. 2,885,083 and, in addition, filter disc unit guide and locator means for controlling disc wobble and preventing contact with the cake slots during rotation of the filter disc units. The new and improved apparatus of the present invention is useful in combination to provide overall advantages and improvements in removal of cake from filter disc units. In addition, particular advantages and improvements have been provided by particular parts of the apparatus which may be used separately with other types of disc filter apparatus. Among the advantages and improvements of the present invention are the provision of:
(1) a more rigid, relatively low cost, main scaper blade member having more accurate closely controlled dimensional characteristics to reduce alignment problems caused by bending and distortion in use and in manufacture resulting in loss of maintenance of a uniform width gap between the scraper blade and the filter media side surfaces; PA1 (2) combination cake scraping and blade supporting shoe devices which enable very accurate positioning of the scraper blade member relative to the filter media side surfaces and also continuously scrapes off and removes cake from the shoe support surfaces on the filter disc unit to maintain continuous slidable abutting supporting contact between the shoe and the shoe support surfaces to overcome the prior art problem of cake build-up on the shoe support surfaces which lifted the blade member away from the filter media side surfaces to preclude maintenance of a uniform blade-filter media surface gap; PA1 (3) filter disc unit guide and abutment devices mounted in the disc unit rotational slots on the cake removal side of the tank means to prevent excessive wobble of the filter disc unit and to prevent contact between the filter disc unit and the side plates of the cake removal slots; and PA1 (4) blade mounting bracket means which enable rigid accurate adjustable mounting of the scraper blade member relative to the filter disc unit while facilitating the accurate assembly of the parts and reducing the time required for accurate assembly of the parts. PA1 A. main cake scraper blade assembly means having a one piece member of elongated metal plate material formed into a rigid cross-sectional configuration including: PA1 B. cake scraping and blade supporting shoe means, preferably made of one piece of molded plastic material, mounted on the radially innermost and on the radially outermost end portions of the scraper blade means for both PA1 C. radially innermost and outermost blade mounting bracket assembly means for pivotally supporting the scraper blade means radially across the filter disc segments of the associated filter disc unit in fixed axially spaced relationship to the associated filter media surface while enabling axial displacement with the filter disc unit during wobble, the radially innermost mounting bracket assembly means including: PA1 D. filter disc unit guide and abutment means, having an abutment block member, preferably made of one piece of molded plastic material, mounted on the side plates of the cake removal slot means for intermittent sliding abutting engagement with the radially outermost filter media support surfaces of the filter disc segments of the associated filter disc unit to limit disc wobble within predetermined axial variation limits and to prevent contact with the cake removal slot side plates.
In general the new and improved apparatus of the present invention comprises:
(1) a relatively narrow width axially inner most rigid elongated flange portion located axially next adjacent the associated radially and circumferentially extending filter media surface and being inclined relative thereto at a first acute angle of inclination relative thereto and extending axially outwardly and away therefrom in the general direction of rotation of the associated filter disc unit; PA2 (2) a relatively wide rigid elongated central panel portion rigidly connected to and located axially next adjacent to and being inclined relative to the inner flange portion and also being inclined relative to the adjacent associated filter media surface at a second acute angle of inclination relative thereto, less than the first angle of inclination of the innermost flange portion, and also extending axially outwardly and away from the adjacent associated filter media surface in the general direction of rotation; and PA2 (3) a relatively narrow width elongated rigid axially outermost flange portion extending along the entire length of the central panel portion and extending toward the associated filter media surface and intersecting the central panel portion at an acute angle to form a rigid intersection therewith. PA2 (1) supporting and axially locating the scraper blade means relative to the associated filter media surfaces of the filter disc segments of the associated filter disc unit, and PA2 (2) scraping and removing filter cake from the associated radially innermost and outermost circumferentially extending peripheral support surfaces of the filter disc segments of the associated filter disc unit with which the shoe means is normally abuttingly slidably engaged. PA2 (1) a first bracket means mounted on the tank means axially adjacent the associated filter disc unit; PA2 (2) a second bracket means mounted on the first bracket means with first blade position adjustment means therebetween for variable adjustment of the circumferential location of the second bracket means relative to the first bracket means and relative to the associated filter disc unit; PA2 (3) a third bracket means attached at one end to and supporting the radially innermost end portion of the central panel portion of the blade member for adjustably connecting the blade member to the second bracket means through pivotal connecting means on an axially extending axially adjustable adjustment shaft means mounted in an axially extending eccentric shaft mounting bore means in a rotatable shaft support sleeve means rotatably mounted on axially extending sleeve mounting bore means in hub means on the second bracket means, the pivotal connecting means enabling swinging movement of the blade member axially inwardly and outwardly with the associated filter disc unit during wobble, the axially adjustable shaft means providing second blade adjustment means enabling substantial axial inward and outward adjustment of the normal operating position of the blade member relative to the associated filter disc unit, the eccentric shaft mounting bore means and the rotatable shaft support sleeve means providing third blade adjustment means enabling limited axial inward and outward adjustment as well as simultaneous limited circumferential adjustment of the position of the radially innermost end portion of the blade member and the radially innermost cake scraping-blade supporting shoe means attached thereto relative to the associated filter disc unit.